Anchovy sprat
Anchovy sprat, Clupeonella engrauliformis, is a species of fish in the family Clupeidae. It is one of several species of Clupeonella found in the Central and Southern Caspian Sea. It lives pelagically in the central and southern parts of this brackishwater lake. It is typically long, and up to maximum. It may be found down to a depth of.
The achovy sprat was first described by ichthyologist N. A. Borodin in 1904 under the name Clupea engrauliformis. The holotype is 124 mm in length, was caught near Cape Buynak in the Caspian Sea and is stored in the .
Description
The maximum body length is 16.5 cm, with a mass up to 26 g.The body of the fish is elongated and low, with its height comprising 16-19% of the body length. The scales easily fall off. Its head is short and wide, with the interorbital distance being 16-18% of the body length and a small mouth. The abdomen of the achovy sprat is rounded with a keel, in which there are 23-31 keeled scales. There are 56-67 gill rakers. the dorsal fin has 13-21 soft rays with the first three being unbranched. the anal fin has 18-22 soft rays with the first three also unbranched. The tail fin is almost black and strongly notched. The edges of the pectoral fins are pointed. The back is dark with a greenish tint. Females are usually slightly larger than males.
Biology
The achovy sprat is a schooling pelagic fish that mainly inhabits open waters but occasionally approaches shores. In spring and autumn it rises to the surface, though most of the year is spent at depths up to 78 metres. It is found at water temperatures from 6 to 28 °С and salinity of 8-13%. It performs daily vertical and seasonal migrations. The difference between the mitochondrial genomes of anchovy and Black and Caspian Sea sprats concerns 449 bp, including two insertions in the control region, unknown in other representatives of the genus Clupeonella. The differentiation of tyulkas is probably related to the transgression and degradation of the Pontic Lake-Sea: it began in the Miocene, continued in the Pliocene, and was completed by the Pleistocene. The modern differences of tyulkas may be connected with different adaptations of their ancestors to specific conditions in different water bodies—remnants of the Pontic Mega-lake.Diet
The basis of its diet consists of copepods, and it feeds on zooplankton during the daytime, especially Eurytemora grimmi. To a lesser extent it consumes cladocerans, mysids and mollusk larvae.Its natural enemies are Brazhnikov's shad, Caspian seal and sturgeons.